Fig. 1. Scanning electron microscopy images of (a) pure goethite, and goethite coated with polygalacturonate of different C loadings: (b) 5.5 mg C g^–1, (c) 7.6 mg C g^–1, and (d) 10 mg C g^–1. Multidomainic goethite crystals are visible in Fig. 1a; Fig. 1b shows in more detail the clustering of goethite crystals induced by PGA at low PGA-C content; Fig. 1c and 1d give overviews of PGA-goethite clusters on differently sized aggregates of goethite.